RuntimeLibrary

Status of the support of the OpenCL runtime library

Sources: OpenCL 1.2 Reference Pages, section OpenCL Platform, OpenCL 1.2 Specification, OpenCL 1.2 Extension Specification

General

Only EMBEDDED_PROFILE is supported, since the implementation does not support 64-bit integers. More so, the 64-bit and 16-bit floating point extensions are unsupported, as well as anything which has to do with images or OpenGL inter-operability. Since access to the memory (shared with the CPU), is always synchronized among all QPUs, all cl_khr_xxx_atomics extensions are supported.

Query Platform Info

clGetPlatformIDs - returns a single platform for the VideoCore IV implementation
clGetPlatformInfo - supports all parameters specified in OpenCL 1.2

Query Devices

clGetDeviceIDs - returns a single device of the type CL_DEVICE_TYPE_GPU (which is also CL_DEVICE_TYPE_DEFAULT) representing the VideoCore IV GPU
clGetDeviceInfo - supports all parameters specified in OpenCL 1.2. Supports 1 compute unit with 12 work-items (12 QPUs) has a preferred vector-width or all supported types of 16 elements (since a QPU is a virtual 16-way SIMD). Long, Double and Half types are unsupported. The device is a 32-bit lower endian processor and has a default clock rate of 250MHz. The graphic memory is shared with the host memory and its maximum size can be configured via the /boot/config.txt or tools such as raspi-config (the setting is called memory-split). Images are not supported, neither is printf and device-partitioning/sub-device creation. Compiler is supported, if the library is compiled with the VC4C compiler.

Partition a Device

clCreateSubDevices - not supported
clRetainDevice - not supported
clReleaseDevice - not supported

Contexts

clCreateContext - supported
clCreateContextFromType - supported
clRetainContext - supported
clReleaseContext - supported, automatically cleans up context and all its children object
clGetContextInfo - supports all parameters specified in OpenCL 1.2.

Command Queues

clCreateCommandQueue - supported, commands are always executed in-order, disregarding the value of CL_QUEUE_OUT_OF_ORDER_EXEC_MODE_ENABLE. Profiling is supported if and only if CL_QUEUE_PROFILING_ENABLE is specified.
clRetainCommandQueue - supported
clReleaseCommandQueue - supported, automatically cleans up command queue and all its children
clGetCommandQueueInfo - supports all parameters specified in OpenCL 1.2.

Buffer Objects

clCreateBuffer - supported, the buffer is immediately allocated on the device-memory
clCreateSubBuffer - supported
clEnqueueReadBuffer - supported
clEnqueueWriteBuffer - supported
clEnqueueReadBufferRect - supported
clEnqueueWriteBufferRect - supported
clEnqueueFillBuffer - supported
clEnqueueCopyBuffer - supported
clEnqueueCopyBufferRect - supported
clEnqueueMapBuffer - supported, device-memory is always mapped to host-memory
clCreateImage - images are not supported
clGetSupportedImageFormats - images are not supported
clEnqueueReadImage - images are not supported
clEnqueueWriteImage - images are not supported
clEnqueueFillImage - images are not supported
clEnqueueCopyImage - images are not supported
clEnqueueCopyImageToBuffer - images are not supported
clEnqueueCopyBufferToImage - images are not supported
clEnqueueMapImage - images are not supported
clEnqueueUnmapMemObject - supported, device-memory is always mapped to host-memory
clEnqueueMigrateMemObjects - supported, no-op, memory objects are always located on the device
clGetMemObjectInfo - supports all parameters specified in OpenCL 1.2
clGetImageInfo - images are not supported
clRetainMemObject - supported
clReleaseMemObject - supported, automatically cleans up device memory
clSetMemObjectDestructorCallback - supported

Sampler Objects

clCreateSampler - always returns CL_INVALID_OPERATION, since images and samplers are not supported
clRetainSampler - supported
clReleaseSampler - supported
clGetSamplerInfo - supported

Program Objects

clCreateProgramWithSource - supported, supports OpenCL source as well as LLVM IR and SPIR-V as source code
clCreateProgramWithBinary - supported, supports platform-dependent binary format (e.g. as output of VC4C)
clCreateProgramWithBuiltInKernels - supported, but there are no supported built-in kernels
clRetainProgram - supported
clReleaseProgram - supported, releases program and all its resources automatically
clBuildProgram - only supported, when compiled with the VC4C compiler
clCompileProgram - only supported, when compiled with the VC4C compiler
clLinkProgram - only supported, when compiled with the VC4C compiler
clUnloadPlatformCompiler - supported, but no-op
clGetProgramInfo - supports all parameters specified in OpenCL 1.2
clGetProgramBuildInfo - supported

Kernel Objects

clCreateKernel - supported
clCreateKernelsInProgram - supported
clRetainKernel - supported
clReleaseKernel - supported, the kernel and all its resources are automatically freed
clSetKernelArg - supported
clGetKernelInfo - supports all parameters specified in OpenCL 1.2. There is no way to retrieve the content of CL_KERNEL_ATTRIBUTES.
clGetKernelWorkGroupInfo - supported
clGetKernelArgInfo - supports all parameters specified in OpenCL 1.2.

Executing Kernels

clEnqueueNDRangeKernel - supported
clEnqueueTask - supported
clEnqueueNativeKernel - supported, but no native kernels available

Event Objects

clCreateUserEvent - supported
clSetUserEventStatus - supported
clWaitForEvents - supported
clGetEventInfo - supports all parameters specified in OpenCL 1.2.
clSetEventCallback - supported
clRetainEvent - supported
clReleaseEvent - supported, automatically frees the event

Markers, Barriers, and Waiting

clEnqueueMarkerWithWaitList - supported
clEnqueueBarrierWithWaitList - supported

Profiling Operations on Memory Objects and Kernels

clGetEventProfilingInfo - supports all parameters specified in OpenCL 1.2.

Flush and Finish

clFlush - supported, but is no-op since all events are automatically flushed
clFinish - supported

Extensions

Khronos ICD loader (cl_khr_icd)

See ICD loader specification for details.

clIcdGetPlatformIDsKHR - supported, returns the 1 global platform
clGetExtensionFunctionAddress - supported

SPIR Binaries (cl_khr_spir)

See SPIR Binaries for details.

Intermediate Language Programs (cl_khr_il_program)

See Intermediate Language Programs for details.

clCreateProgramWithILKHR - supported, but optional, since CreateProgramWithSource also accepts SPIR-V source

Querying device temperature (cl_altera_device_temperature)

See extension specification for details.

Tracking live objects (cl_altera_live_object_tracking)